1. Field of the Invention
The present invention relates to playback of a storage medium, and more particularly, to a storage medium in which text-based subtitle data including style information is recorded, and an apparatus and a method of playing back the storage medium.
2. Description of the Related Art
Generally, storage media, such as, digital versatile displays (DVDs), store audio-visual (AV) data, which includes video data and audio data. The stored video data and audio data in the AV data are compressed according to a standard such as the motion picture experts group (MPEG) standards. The AV data optionally includes subtitle data. Hereinafter, AV data is referred to as moving image data.
Conventional storage media, such as, DVDs, use bitmap-based sub-picture data as subtitle data for providing a subtitle of a moving image. The sub-picture data has been compressed together with a video stream, an audio stream, and the like according to a standard, such as, MPEG2 or the like. When subtitle data is provided using conventional bitmap-based sub-picture data, the subtitle data is accurately synchronized with video stream data.
However, the use of bitmap-based sub-picture data causes the following problems. First, because a subtitle is provided using a bitmap-based image, an output style of a subtitle reflected upon the manufacture of an image corresponding to the subtitle cannot be changed. Second, because sub-title data is multiplexed with a video stream, an audio stream, and the like, it is difficult to add new sub-title data to the multiplexed sub-title data or correct existing sub-title data. Third, the number of subtitle data that can be added is restricted to prevent degradation of the quality of an image.